0428同步年報-2021-全

080 ACTIVITY REPORT 2021 unit cell is double the nuclear unit cell. The temperature dependence of the magnetic peak intensity is plotted in Fig. 1(c) ; the magnetic structure is illustrated in Figs. 2(a) and 2(b) . The ordered Cu 2+ moments are about 0.75 μ B at 3.5 K and lie in plane a - c . The typical spin structure of the frustrated bow-tie lattice is realized in the Cu2-Cu3 layer, in which the Cu3 spins form sequence (++--) along axis a , which might invoke magnetoelectric coupling through the exchange-striction effect. In the case of Cu 9 O 2 (SeO 3 ) 4 Cl 6 , the propagation vector is found to be q = (1/2 1/2 0), indicating that the magnetic unit cell is double the nuclear unit cell along axes a and b ( Fig. 1(d) ). The temperature dependence of the magnetic peak intensity is plotted in Fig. 1(d) ; the magnetic structure is illustrated in Figs. 2(c)–2(e) . The magnetic moments lie in plane a - c forming a non-collinear antiferromagnetic structure. Half of Cu(5) ions carry no moments as required by the magnetic symmetry group, showing that the spins of Cu(5) ions still fluctuate, even below T N , and carry no static magnetic moment. In summary, Yang’s group successfully synthesized α-Cu 5 O 2 (SeO 3 ) 2 Cl 2 and Cu 9 O 2 (SeO 3 ) 4 Cl 6 single crystals with a chemical vapor-transport method and investigated the structural, magnetic and dielectric properties. Neutron powder diffraction provided information about the magnetic order and magnetic structures. (Reported by Chin-Wei Wang) This report features the work of Hung-Duen Yang and his collaborators published in Mater. Adv. 2 , 7939 (2021) and Phys. Rev. B 100 , 245119 (2019). TPS 09A Temporally Coherent X-ray Diffraction ANSTO WOMBAT – High-intensity Powder Diffractometer • XRD, NPD • Condensed-matter Physics References 1. D. C. Kakarla, Z. H. Yang, H. C. Wu, T. W. Kuo, A. Tiwari, W.-H. Li, C. H. Lee, Y.-Y. Wang, J.-Y. Lin, C. K. Chang, B. H. Chen, C.-W. Wang, C. A. Lee, M. M. C. Chou, H. D. Yang, Mater. Adv. 2 , 7939 (2021). 2. H. C. Wu, K. N. Denisova, D. Menzel, D. C. Kakarla, O. V. Maximova, T. W. Kuo, Z. H. Yang, C. H. Lee, W. H. Li, H. Berger, C. W. Wang, C. K. Chang, Y. C. Chuang, J.-Y. Lin, M. Gooch, C. W. Chu, A. N. Vasiliev, H. D. Yang, Phys. Rev. B 100 , 245119 (2019). Fig.2 : Magnetic structure of α-Cu 5 O 2 (SeO 3 ) 2 Cl 2 illustrated as (a) stacking along the crystallographic b -axis direction and (b) projection of Cu2 and Cu3 spins in crystallographic plane a-c . Dashed rectangular blocks indicate ferromagnetic spin-dimers that form along the a -axis direction. Non-collinear antiferromagnetic structure of Cu 9 O 2 ( S eO 3 ) 4 Cl 6 : (c) stacking of Cu layers along the crystallographic b -axis direction, (d) Cu spin configuration in layer A, and (e) Cu spin configuration in layer B. [Reproduced from Ref. 1 and Ref. 2]